General Oriented Synthesis of Precise Carbon-Confined Nanostructures by Low-Pressure Vapor Superassembly and Controlled Pyrolysis.

Earth-abundant metal-based nanostructured materials have been widely studied for potential energy conversion and storage. However, controlled synthesis of functional nanostructures with high electron conductivity, high reaction activity, and structural stability is still a formidable challenge for further practical applications. Herein, for the first time, we develop a facile, efficient, and general method for the oriented synthesis of precise carbon-confined nanostructures by low-pressure vapor superassembly of a thin metal-organic framework (MOF) shell and subsequent controlled pyrolysis. The selected nanostructured metal oxide precursors not only act as metal ion sources but also orient the superassembly of gaseous organic ligands through the coordination reactions under the low-pressure condition, resulting in the formation of a tunable MOF shell on their surfaces. This strategy is further successfully extended to obtain various precise carbon-confined nanostructures with diverse compositions and delicate morphologies. Notably, these as-prepared carbon-confined architectures exhibit outstanding electrochemical performances in water splitting and lithium storage. The remarkable performances are mainly attributed to the synergistic effect from appropriate chemical compositions and stable carbon-confined structures. This synthetic approach and proposed mechanism open new avenues for the development of functional nanostructured materials in many frontier fields.